Need for a Vapor Retarder Omaha NE

Typically, either foil-faced polyisocyanurate or extruded polystyrene insulation can be used in cavity wall systems in Omaha. Both of these rigid insulation materials will also function as vapor retarders. A wall system consisting of a masonry veneer, a cavity with rigid insulation, and an interior concrete masonry wall will be effective in most climates.

Stetson Building Products Inc
(402) 331-0333
6820 J St
Omaha, NE
 
Midwest Construction Products
(402) 392-7383
3030 Keystone Dr
Omaha, NE
 
Bradco Supply
(402) 731-0588
7700 F St
Omaha, NE
 
Stetson Building Products
(402) 331-0306
6820 J St
Omaha, NE
 
Armor Industries Inc
(402) 571-5458
9215 Fremont St
Omaha, NE
 
Builders Supply Co Inc
(402) 331-4500
5701 S 72nd St
Omaha, NE
 
Arctic Insulation Inc
(402) 457-5064
8615 N 29th St
Omaha, NE
 
Proven Products
(402) 827-3880
5010 I St
Omaha, NE
 
84 Lumber
(402) 758-0084
15001 W Center Rd
Omaha, NE
 
Midstates Construction Products Inc
(402) 331-4548
4103 S 67th St
Omaha, NE
 

Need for a Vapor Retarder

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Source: MASONRY CONSTRUCTION MAGAZINE
Publication date: October 1, 2000

Is a vapor retarding membrane required in an insulated masonry cavity wall?

Determining the need for a vapor retarder is a decision that should be reviewed with a knowledgeable mechanical engineer. Depending on the exterior wall construction, vapor-retarding membranes can be omitted in an insulated cavity wall in most parts of the United States. Typically, either foil-faced polyisocyanurate or extruded polystyrene insulation can be used in cavity wall systems. Both of these rigid insulation materials will also function as vapor retarders. A wall system consisting of a masonry veneer, a cavity with rigid insulation, and an interior concrete masonry wall will be effective in most climates. In the northern parts of the United States, the predominant vapor drive occurs during cold outdoor temperatures from the interior to the exterior. In these conditions, the dew point will occur within the insulation. Because the insulation serves as its own vapor retarder, there should not be a problem. The same is true for the southeastern United States, where the primary vapor drive is from the exterior to the interior during the hot humid summer months.

In regions with a northern climate, such as northern Minnesota or Canada, hospitals and other buildings that must be pressurized may require a vapor-retarding membrane that also functions as an effective air barrier. In these cases, it is often best to parge the exterior surface of the concrete masonry with approximately 1/2 inch of parging. This parge coat can be covered with a vapor-retarding membrane that can be installed and inspected on the exterior prior to the installation of the rigid insulation and brick outer wythe. In hospitals humidified and pressurized relative to the exterior, this will help prevent moisture-laden interior air from moving through and condensing within the wall system, causing moisture problems.


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